Portable electronic devices are generally controlled by input devices located on the portable device, such as a button, or pen touch computing. A typical portable electronic device 20 is depicted in Prior Art FIG. 1, and includes a display screen 24, and a control area 25, an input touch area 26, an adapter 28 and a series of control buttons 30, 32, 34, 36, and 38. The display is usually controlled by the pen input to a scroll bar in the screen control area 25, or a control buttons 30, 32, 34, 36, and 38
Other methods have been developed to control the display of a portable electronic device with the use of user initiated motion. One such method invented by the applicant is embodied in U.S. Pat. No. 6,184,847, which is represented by prior art FIG. 2 in which the display of the portable electronic device 20 responds to user controlled motion of a user 100. Other devices such as the Compaq Rock-n-Scroll™ represented by prior art FIG. 3A and FIG. 3B, use only user's 100 tilt of the portable device 20 to control the display. Such portable devices 20 usually comprise multiple sensing devices such as accelerometers in order to detect user initiated motion. Such devices usually require the use of multiple accelerometers which can add greatly to the expense of the portable device.
Additionally, the calculation required from the input of several accelerometers can add greatly to the computational problems of controlling a display with such types of motions sensors. Although, simple threshold types of motions such as a 45 degree tilt can easily control a display for simple commands such a scroll left or scroll right, calculation that requires more fine tuning will use a great deal more computing power to integrate the data from the three accelerometer or gyroscope readings. For example the motions of the portable device will result in logic having to integrate the voltage readings from two accelerometers.
The accelerometer can be used to measure motion in any direction, including a “tilting” of the device. The distance an object has been moved is the integral of velocity over time. Essentially, the integral is a fairly complicated calculation on a device that may be running less than 8 M or RAM and while single calculations do not present a serious problem, continuous calculation from constant movement will require a great deal of system resources.
Normally, to measure the distance and object has traveled with accelerometers, it is necessarily to integrate twice. This amount of integration can lead to a great deal of error, even with the most accurate of accelerometers, what is needed is a way to predict some of the parameters of motion based on a normal users movement, instead of integrating several accelerometers at the same time.
What is needed is a method of calculating the motion or position of a portable device that does not require the expense and computational complexity of multiple accelerometers or other motion sensor, in order to control the display of the device.